The present invention relates to the fields of vascular and cardiovascular surgery, and more particularly to methods and devices for obtaining arterial or vascular occlusion when performing graft procedures.
Vascular and cardiovascular grafting procedures typically require the complete, or at least partial, occlusion of a selected vessel. For example, in the field of cardiovascular surgery, coronary artery bypass graft (CABG) procedures involving proximal anastomosis require the full, or at least partial, occlusion of the aorta. During proximal anastomosis, a vein or arterial graft is sewn to the aorta for revascularization of diseased or otherwise compromised coronary arteries. The internal mammary artery and radial artery of the arm are also used as bypass vessels. Occlusion of the aorta is typically accomplished by clamping. A variety of clamp configurations are in common use, including crossclamps for partial occlusion procedures. For procedures involving cardiopulmonary bypass, full aortic occlusion is required. Partial occlusion is used in either on or off-pump coronary artery bypass graft procedures for proximal anastomosis. Occlusion of the aorta prevents blood flow from entering the graft target site, creating a bloodless field for the surgeon to then sew the graft to the aorta. Once the graft is sewn to the aorta, the surgeon removes the clamp, once again allowing blood flow to the anastomotic region.
Unfortunately, injury resulting from such clamping can be significant. Such injuries include, but are not limited to, intimal hyperplasia, thrombosis (which may progress to total occlusion), embolism, intimal tears and flaps, mural dissections, aneurysms, arterial rupture, through-and through injury, and arterio-venous fistulae. As just one example, neurologic morbidity after cardiac surgery has been associated with particulate embolization. Crossclamp manipulation has been identified as the single most significant cause of particulate emboli release during cardiac surgery. Therefore, surgeons would prefer to eliminate the use of clamps during coronary artery bypass graft procedures in order to minimize adverse events and improve outcomes.
Efforts have been made to devise alternative devices and methods for performing bypass graft procedures that avoid complete clamping or crossclamping of the aorta. For example, U.S. Pat. No. 5,477,515 describes a bypass clamp with a spoon-shaped blade insertable through an incision in the aorta. Patches of saphaneous vein or other substitute are sutured on either side of the incision to reinforce the aorta and prevent tearing or abrasion by the clamp. U.S. Pat. No. 5,944,730 describes a device for creating a seal at an incision that includes a tube with a translatable shaft connected to a flexible inverting member. The inverting member is inserted into the incision and proximal force applied to the device creates a seal. Other methods have relied upon inflatable devices for partially occluding a vessel without interrupting blood flow. U.S. Pat. No. 6,143,015 describes such a device which includes first and second inflatable spaced apart members interconnected by a tubular connector that allows for blood flow.
Despite these efforts, there remains a need to provide for an anastomosis occlusion device that minimizes the adverse events associated with conventional clamping and crossclamping techniques, avoids trauma to the vessel and graft site, and that is versatile, and easy-to-use.
The present invention meets the above needs and achieves further advantages by providing for an anastomosis occlusion device and methods for use in grafting procedures that minimize trauma and adverse events associated with grafting procedures, including trauma and adverse events currently associated with coronary artery bypass graft procedures.
In particular, the invention provides for a low-profile shaft assembly that is configured for insertion into the lumen of the aorta (or other selected vessel) and that includes an expandable region at the distal end of the shaft assembly. The expandable region includes a sealing membrane that spans across the expandable region. Once inserted into the lumen of the aorta (or other selected vessel) this expandable region can be deployed from a first low-profile position into a second expanded position, and positioned at the target site of the anastomosis. A clamping member, located outside the vessel, is also provided having a distal end that is shaped to correspond to the expandable region of the shaft assembly in its second expanded position. Movement of the distal end of the clamping member against the expanded region creates a seal at the target site, defined by the border of the expanded region of the shaft assembly and the sealing membrane. This sealed-off area is thus temporarily segregated from bloodflow at the target site to facilitate performing a grafting procedure without undue blood pressure or leakage interfering with the procedure.
One of the many advantages of the invention is that the insertion site of the device and means for deploying the expandable region from the first low-profile position to the second expanded position, as well as means for moving the clamping member toward the expandable region, are located remote from the anastomosis site. This remote location of these features allows for a less cluttered surgical field at the graft site itself, giving the surgeon a clearer field of view and more room to perform the procedure. Another of the many advantages of the invention is in the low-profile nature of the shaft assembly itself. By xe2x80x9clow-profilexe2x80x9d it is meant that the distal end of the shaft assembly, in its non-deployed, low-profile position, has a cross-sectional profile that is the same as, or only slightly larger, than the cross-sectional profile of remainder of the shaft assembly. This minimizes the size of the incision, puncture, or stick necessary to introduce the shaft assembly into the vessel and otherwise minimizes trauma to the vessel during insertion of the shaft assembly into the vessel. In many cases, the insertion site will be self-sealing upon removal of the assembly, or will otherwise at most require very minimal suturing. In addition, because the expanding region is deployable to its expanded position after its insertion into the vessel, the invention allows for the use of specific instrument configurations that would otherwise not be feasible to introduce directly through a vessel wall without unwarranted trauma to the vessel. For example, the specific configurations that are attainable by deploying the expanding region of the present invention after insertion into the vessel would otherwise require making large incisions to accommodate their introduction into the vessel.
In one embodiment of the invention, a shaft assembly is provided having a flexible tube extending over the shaft assembly with the distal end of the flexible tube secured to the distal end of the shaft assembly. The distal end of the flexible tube further includes an expanding region having bowing portions, with a sealing membrane attaching to the bowing portions. Movement of the flexible tube relative to the shaft assembly in the direction of the distal end of the assembly causes the bowing portions to bow outward, creating the expanded region of the assembly, with the sealing membrane spanning the expanded region.
In another embodiment of the invention, the shaft assembly includes a fixed shaft and a rotatable shaft that are axially aligned, each of which has corresponding bowing portions at the distal end of the respective shafts that extend away from the axis of the assembly. A sealing membrane is secured to and spans the bowing portions of the shafts. Rotation of the rotatable shaft causes the bowing portions of the shafts to become spaced apart from one another, creating an expanded region with the sealing membrane extending across the region.
Control of the deployment of the expandable region and movement of the clamping member toward the expandable region can either be operably linked or independent. In one embodiment of the invention, the clamping member includes an actuator that engages a slide that in turn engages the shaft assembly. Movement of the clamping member toward the expandable region moves the slide via the actuator, which then simultaneously moves the shaft assembly, resulting in the deployment of the expandable region. Alternatively, the invention also provides for deployment of the expandable region and movement of the clamping member independently. In one such embodiment, the shaft assembly includes the described axially aligned fixed and rotatable shafts which control deployment of the expandable region. The shaft assembly and clamping member are pivotally linked and also include handles, such that actuation of the handles moves the shaft assembly and clamping member independent of the expandable region deployment. In another embodiment, the clamping member is controlled by a turn screw mechanism and the deployment of the expandable region is controlled by an independent slide actuator.
In another embodiment of the invention, a device is provided having a housing with a clamping member pivotally mounted to the housing and a slide located within the housing and moveable from a first position to a second position. A shaft assembly is connected to the slide and extends therefrom. A flexible tube extends over the shaft assembly, the proximal end terminating near the housing and the distal end secured to the distal end of the shaft assembly. The distal end of the flexible tube includes an expanding region having first and second bowing portions, with a sealing membrane attaching to said bowing portions. The clamping member includes an actuator which engages the slide and a lever arm extending from the clamping member and terminating in a distal end defining a particular geometry. Upon movement of the clamping member, the actuator causes movement of the slide and shaft assembly, and the distal end of the flexible tube is displaced, forcing the bowing portions to bow outward, creating an expanded region of the tube with the sealing membrane stretched over the region. The distal end of the lever arm is shaped in a complementary pattern to the expanded region.
In use, the shaft assembly of a device according to the invention is introduced into the lumen of the aorta until the distal end of the tube is positioned beneath a target region at the graft site. A hole is created at the target region, either prior to or after positioning of the device. Actuation of the device clamps the vessel wall between the top clamp and expanded region of the flexible tube of the device, creating a seal against blood flow into the graft area. The surgeon can then proceed with performing the anastomosis in an essentially bloodless field.
In another embodiment of the invention, an occlusion device is provided having a shaft assembly and a clamping member pivotally mounted for movement toward and away from one another. The shaft assembly includes a fixed shaft and a rotatable shaft that are axially aligned, each of which has corresponding bowing portions at the distal end of the respective shafts that extend away from the axis of the assembly. A sealing membrane is secured to and spans the bowing portions of the shafts. Rotation of the rotatable shaft causes the bowing portions of the shafts to become spaced apart from one another, creating an expanded region with the sealing membrane extending across the region. The clamping member that is pivotally mounted for movement toward the shaft assembly includes a distal end having a configuration that corresponds to the expanded region of the shaft assembly when the bowing portions are in the described spaced apart configuration. In operation, the shaft assembly is introduced into the aorta, and then the bowing portions are deployed into the spaced apart configuration at the graft site. The clamping member is then moved toward the shaft assembly, clamping the vessel wall between the distal end of the clamping member and the distal end of the shaft assembly in the deployed, spaced apart configuration, creating a sealed off area for performing the graft.
In yet another embodiment of the invention, an occlusion device is provided having a housing with a slide located within the housing that is moveable from a first to a second position. A shaft assembly extends from the housing and includes a control rod extending through the length of the shaft assembly, an expandable region at the distal end of the shaft assembly, and a sealing membrane likewise at the distal end of the shaft assembly that spans the expandable region. The control rod is connected at its proximal end to the slide and at its distal end to the distal end of the shaft assembly. The expandable region is deployable from a first, low-profile position to a second expanded position. A clamping member is pivotally mounted to and extends from the housing. The distal end of the clamping member is shaped to correspond to the expandable region of the shaft assembly in its second expanded position. The device includes separate, independent actuators for deploying the expandable region of the shaft assembly into its expanded position and for pivotally moving the clamping member toward and away from the shaft assembly.
In another aspect of the invention, a lumen in fluid connection with an injection port and one or more delivery ports that open to the surface of the shaft assembly are provided, thus allowing for convenient means for delivering tissue adhesives, sealants or other agents to the anastomosis site, as well as allowing for general means of administering an agent into the bloodstream.
In yet another aspect of the invention, a filter is provided that is deployable downstream of the anastomosis site. The filter can collect and trap any debris or particulate matter that is loosened from the vessel wall during the anastomosis procedure.
In a further aspect of the invention, an occlusion device according to the invention is provided that is adapted for laproscopic use.